Case Capacity In Water .338/378 And .338 Lapua

[Nitroman]

I am reloading for the .338 A-Square, which is made off the .378 or .338/378 Weatherby case. The A-Square has much more sloping sides and is about 0.10" shorter.

I weighed a random, fired case and then added water, reweighed and subtracted for 127.7gr water using my RCBS Chargemaster scale.
(Note: I filled to the case mouth).

I then did this with my RCBS 10-10 balance using a dry case (fired using the same load), with the case weighing 316.2gr. and with water 443.4gr. for 127.2gr capacity water. Okay.

I look at Wiki for the .338/378 which gives 124gr. water. Hmmm. I wonder if they filled then weighed to the bottom of the case neck?

Anyone have the capacity of their .338/378 to the top of the mouth? And a .338 Lapua would be helpful as well.

Trying to dial in without burning up too much precious powder. It is expensive to get it here.

Thank you.

 

[Nitroman]

Really? On the only website seriously dedicated to heavy hitters?

I guess I'll have to buy a couple fired cases.

 

[g0rd0]

I believe that you made a mistake on working out your case capicty
first you need 10 fired cases from your rifle, all the same brand cleaned neck sized then trimmed.
Now without a primer or powder place a lubed bullet in the case mouth just enough to hold it in place and chamber it.
Now weigh the dummy write down the weight and then use a hypo needle (get them at your farm supply store), and fill up the dummy with h2o through the flash hole. Wipe dry the primer pocket and weigh then subtract to get your CC.
Add all 10 CC's divide by 10 to get your average CC

With different bullets and brass you will get different CC witch will change your expantion ratio

 

[HARPERC]

If you're wanting load info, Loaddata.com has some. If you're looking for specifically a case capacity comparison you'll have to wait until someone's digested their holiday dinner, and is ready to play again.

The little loading data I looked at, was producing results so close there can't be much difference.

 

[Nitroman]

Thank you gentlemen. More info to digest as well.